Meaning "hard stone", and sometimes
known as "Florentine mosaic", this is intricate inlay work from
thin pieces of coloured stone. The pieces are cut to fit together
perfectly, in a similar way to opus sectile. This type of mosaic can look
like a painting, as the textured patterns of different types
of stone are used to mimic features such as clouds, leaves, feathers
etc. See also cosmati.